1. Field of the Invention
The present invention relates to an apparatus and method for processing wafers and optical coating, and more particularly, to a high throughput multi-vacuum chamber system for processing wafers and method of processing wafers using the same. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for high wafer throughput, and reduced footprint, thereby providing a low cost of ownership.
2. Description of the Related Art
A wafer process, such as thin film deposition or etching, is generally carried out in a vacuum system. The vacuum system for the wafer process typically consists of vacuum chambers, load lock chambers (or loading door/flange), vacuum pumps, deposition sources, power supplies for the deposition sources, and process control gauges.
A conventional single vacuum chamber system is shown in FIGS. 1A to 1C. A conventional box coater type system shown in FIG. 1A includes a chamber 1, a loading door 2, a pump 3, a valve 4 connecting the chamber 1 and the pump 3, and a deposition source and power supply 5 attached to the chamber 1. FIG.1B shows another conventional system having a chamber 6 with a openable flange 7 for loading wafers. Similar to the box coater system shown in FIG. 1A, the system has a pump 8 and the chamber 6 connected by a valve 9, and a deposition/power source 10. Another type of conventional vacuum system is illustrated in FIG. 1C. This type of system has a load lock chamber 11 attached to a main chamber 12. Wafers (not shown) are transferred to the main chamber 12 through the load lock chamber 11 using a transport arm 13 (or robotic arm). A pump 14 to maintain the system under vacuum condition is connected to the main chamber 12 through a gate valve 15. A deposition/power source 16 is also provided at the bottom of the main chamber 12.
In all of the conventional vacuum systems, however, the wafer process is not able to be performed continuously without breaking the vacuum condition of the chamber when a wafer is loaded or unloaded into the system. As a result, the whole vacuum system including the vacuum pumps is not effectively utilized throughout the process.
Recently, a dual chamber vacuum system for depositing dielectric thin films by plasma-enhanced chemical vapor deposition (PECVD) was discussed in Vacuum & Thin Film, November/December 1998, pages 40 to 43. As shown in FIG. 2, the dual chamber compartment shares a common gas supply 21, a pressure control 22, and one vacuum pump 23. Additionally, RF generators 24, a cathode 25, and an anode 26 are provided to generate a plasma in the vacuum system. By using this structure, a small footprint can be configured to process wafers. Also, throughput can be significantly greater than that of the conventional single chamber system.
Nonetheless, there are some problems in the dual chamber vacuum system shown in FIG. 2. For example, although the system shares a common gas supply, a pressure control, and a vacuum pump, it still needs additional deposition sources (i.e. two RF generators). Further, since wafers in the system are processed simultaneously, they cannot be separately prepared if desired. Therefore, the conventional dual chamber vacuum system still has is some drawbacks such as a higher cost of the system and a lesser degree of flexibility in processing.